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Lab 07: Configuring iSCSI Targets and Multipath I/O (High Availability Simulation)

Alert

This lab is not tested and may result in unexpected outcomes. The idea is to show how iSCSI is configured on TrueNAS

Introduction

In this lab, you will simulate a high availability (HA) SAN setup by configuring iSCSI targets in TrueNAS and enabling Multipath I/O (MPIO) on your Lubuntu VM (from Lab 03). This demonstrates how enterprise servers connect to centralized block storage with redundancy.

By the end of this lab, you will:

  • Enable and configure the iSCSI service in TrueNAS.
  • Create an iSCSI target backed by a ZFS dataset.
  • Simulate multiple network paths to the same target.
  • Configure Multipath I/O (MPIO) on the Lubuntu VM.
  • Verify redundancy and failover.

Step 1: Preparing the Environment

  1. Ensure your TrueNAS VM (FreeNAS-Server) is running with the TechOpsPool from Lab 05.
  2. Ensure your Lubuntu VM (from Lab 03) is running and connected to the same network (Bridged Adapter).
  3. Make sure both VMs can ping each other:
ping <truenas-ip>
ping <lubuntu-ip>

Step 2: Create a Zvol

  1. Browse to Datasets → Click on your TechOpsPool
  2. Click Add Zvol → Zvol name: iscsi_zvol, Size for this zvol: 10 GiB.
  3. Leve all other fields as default
  4. Click on Save

Step 3: Enable iSCSI Service

  • Go to System → Services
  • iSCSI → Running (Select) + Start Automatically (Select).

Step 4: Configure iSCSI Target Wizard

Go to Shares → Block Shares (iSCSI) → Wizard.

  1. Target

    • Target → Create New.

  2. Extent

    • Name: extent0.
    • Extent Type: Device.
    • Device: Select the Zvol (iscsi_zvol).
    • All other settings as default.

  3. Portal Options

    • Portal: Create New
    • IP Address: Add
      • IP Address: 0.0.0.0
    • Initiators: Leave Blank

  4. Click on Save

Step 5: Adding a 2nd NIC in VirtualBox

Power Down TrueNAS VM

  • In VirtualBox main window → select TrueNAS VM
  • Click Close → Power Off (or shut down gracefully inside TrueNAS).

**2. Open VM Settings **

  • Highlight your TrueNAS VM.
  • Click ⚙️ Settings on the toolbar.

Go to Network

  • In the left menu → click Network.
  • You’ll see Adapter 1 already enabled (your current NIC).

Enable Adapter 2

  • Click the Adapter 2 tab.
  • Tick ✅ Enable Network Adapter.

Configure Adapter 2

  • Attached to: Bridged Adapter
  • Name: Select your host’s actual physical network interface (e.g. Wi-Fi card or Ethernet port).
  • Promiscuous Mode: Allow All (recommended for iSCSI multipath so no weird filtering happens).
  • Cable Connected: ✅ checked.

Save & Boot

  • Click OK.
  • Start the TrueNAS VM.

Change your network settings for 192.x.x.x

  • Go to Networks from right side menu
  • Under the Interfaces -> Note down your both of the IPs that are listed
  • Click on Pencil icon of the interface which has IP starting from 192.168.x.x
  • Unselect DHCP
  • Unselect Autoconfigure IPv6
  • Under the Aliases
    • Enter the IP that you have noted down which started from 192.168.x.x and /24
  • Click on Save
  • On the Networks page you will see Test Changes button
  • Above the said button you will see Test network interace changes for **60** seconds
  • Click on the 60 and change to 10
  • Click on 'Test Changes`
  • Click on Confirm and Save Changes
  • Immediately you will see another button on page saying Save Changes click on that within 10** seconds.

Change your network settings for NAT network

  • Go to Networks from right side menu
  • Under the Interfaces -> Note down your both of the IPs that are listed
  • Click on Pencil icon of the interface which has IP starting from 10.0.x.x
  • Unselect DHCP
  • Unselect Autoconfigure IPv6
  • Under the Aliases
    • Enter the IP that you have noted down which started from 10.0.x.x and /24
  • Click on Save
  • On the Networks page you will see Test Changes button
  • Above the said button you will see Test network interace changes for **60** seconds
  • Click on the 60 and change to 10
  • Click on 'Test Changes`
  • Click on Confirm and Save Changes
  • Immediately you will see another button on page saying Save Changes click on that within 10** seconds.

Add additonal portal

  • In the search above, type portals and select Shares -> iSCSI -> Portals
  • Click on the pencil icon of on the existing portal which will start from 0.0.0.0
  • In the IP Address section:
    • Click on drop down which says 0.0.0.0 and select the IP which you have configured in previous step starting from 10.0.x.x
    • Click on Save
  • Click on Add button:
    • In IP Address section again click on Add
    • Select the IP from drop down which starts from 192.168.x.x
    • Click on Save

Step 6: Connecting Lubuntu to iSCSI Target

  1. On Lubuntu VM, install iSCSI initiator tools:
sudo apt update && sudo apt install open-iscsi multipath-tools -y
  1. Discover iSCSI targets from TrueNAS:
sudo iscsiadm -m discovery -t sendtargets -p <truenas-ip>
sudo iscsiadm -m discovery -t sendtargets -p <second-truenas-ip>
  1. Log in to discovered targets:
sudo iscsiadm -m node -l
  1. Verify with:
lsblk

You should see a new disk (e.g., /dev/sdb).

Step 7: Configuring Multipath I/O (MPIO)

  1. Enable multipath service:
sudo systemctl enable multipath-tools
sudo systemctl start multipath-tools
  1. Check multipath configuration:
sudo multipath -ll

You should see both paths listed to the iSCSI target.

  1. Create a filesystem and mount it:
sudo mkfs.ext4 /dev/mapper/mpatha
sudo mkdir /mnt/iscsi
sudo mount /dev/mapper/mpatha /mnt/iscsi
  1. Verify:
df -h
ls /mnt/iscsi

Step 6: Testing High Availability

  1. From VirtualBox, temporarily disable one network adapter of the TrueNAS VM.
  2. On Lubuntu, run:
multipath -ll

You should still see one active path. 3. Access /mnt/iscsi and create a file:

echo "HA Test File" | sudo tee /mnt/iscsi/test.txt
4. Re-enable the network adapter and verify both paths are restored.

✅ This confirms that multipath I/O maintains connectivity even if one path fails.

Troubleshooting Tips

  • Target not visible: Ensure iSCSI service is enabled on TrueNAS.
  • No multipath device: Restart multipath service and check discovery commands.
  • Login errors: Verify firewall rules and that both NICs are on the same subnet.
  • Performance issues: Allocate more RAM/CPU to TrueNAS VM.

✅ Congratulations! You have successfully configured iSCSI targets on TrueNAS and set up Multipath I/O on Lubuntu to simulate high availability in a SAN environment.